Physical Media and Cabling COM211 Communications and Networks CDA College Theodoros Christophides Email: [email protected][email protected].

Physical Media and Cabling

COM211 Communications and NetworksCDA CollegeTheodoros ChristophidesEmail: [email protected]/site/info-com-technology-ll/

Physical Media

Copper Coaxial Cable - Thick or Thin Unshielded Twisted Pair - CAT 3,4,5,5e&6

Optical Fiber Multimode Singlemode

Wireless Short Range Medium Range (Line of Sight) Satellite

Copper Media: Coaxial Cable

Coaxial cable is a copper-cored cable surrounded by a heavy shielding and is used to connect computers in a network.

Outer conductor shields the inner conductor from picking up stray signal from the air.

High bandwidth but lossy channel.

Repeater is used to regenerate the weakened signals.

Category Impedance Use

RG-59RG-59 75 Cable TV

RG-58RG-58 50 Thin Ethernet

RG-11RG-11 50 Thick Ethernet

Copper Media: Twisted Pair

Twisted-pair is a type of cabling that is used for telephone communications and most modern Ethernet networks.

A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs.

There are two basic types, shielded twisted-pair (STP) and unshielded twisted-pair (UTP).

Shielded Twisted Pair (STP) & Unshielded Twisted Pair (UTP)

Unshielded Twisted Pair (UTP)

Consists of 4 pairs (8 wires) of insulated copper wires typically about 1 mm thick.

The wires are twisted together in a helical form. Twisting reduces the interference between pairs

of wires. High bandwidth and High attenuation channel. Flexible and cheap cable. Category rating based on number of twists per

inch and the material used CAT 3, CAT 4, CAT 5, Enhanced CAT 5 and

now CAT 6.

UTP Categories

UTP comes in several categories that are based on the number of twists in the wires, the diameter of the wires and the material used in the wires.

Category 3 is the wiring used primarily for telephone connections.

Category 5e and Category 6 are currently the most common Ethernet cables used.

Cat3 and Cat4

Cat3 Bandwidth 16 Mhz 11.5 dB Attenuation 100 ohms Impedance Used in voice applications and 10baseT (10Mbps) Ethernet

Cat4 20 MHz Bandwidth 7.5 dB Attenuation 100 ohms Impedance Used in 10baseT (10Mbps) Ethernet

Cat5 and Cat5e

Cat5 100 MHz Bandwidth 24.0 dB Attenuation 100 ohms Impedance Used for high-speed data transmission Used in 10BaseT (10 Mbps) Ethernet & Fast Ethernet (100 Mbps)

Cat5e 150 MHz Bandwidth 24.0 dB Attenuation 100 ohms Impedance Transmits high-speed data Used in Fast Ethernet (100 Mbps), Gigabit Ethernet (1000 Mbps) & 155

Mbps ATM

Cat6

1. 250 MHz Bandwidth

2. 19.8 dB Attenuation

3. 100 ohms Impedance

4. Transmits high-speed data

5. Used in Gigabit Ethernet (1000 Mbps) & 10 Gig Ethernet (10000 Mbps)

Fiber

Optical fibers use light to send information through the optical medium.

It uses the principal of total internal reflection.

Modulated light transmissions are used to transmit the signal.

Fiber

Light travels through the optical media by the way of total internal reflection.

Modulation scheme used is intensity modulation. Two types of Fiber media :

Multimode Singlemode

Multimode Fiber can support less bandwidth than Singlemode Fiber.

Singlemode Fiber has a very small core and carry only one beam of light. It can support Gbps data rates over > 100 Km without using repeaters.

Single and Multimode Fiber

Single-mode fiberCarries light pulses along single pathUses Laser Light Source

Multimode fiberMany pulses of light generated by LED travel

at different angles

Fiber

The bandwidth of the fiber is limited due to the dispersion effect.

Distance Bandwidth product of a fiber is almost a constant.

Fiber optic cables consist of multiple fibers packed inside protective covering.

62.5/125 µm (850/1310 nm) multimode fiber

50/125 µm (850/1310 nm) multimode fiber

10 µm (1310 nm) single-mode fiber

Fiber

Wireless

Very useful in difficult terrain where cable laying is not possible. Provides mobility to communication nodes. Right of way and cable laying costs can be reduced. Susceptible to rain, atmospheric variations and Objects in

transmission path. Indoor : 10 – 50m : BlueTooth, WLAN Short range Outdoor : 50 – 200m: WLAN Mid Range Outdoor : 200m – 5 Km : GSM, CDMA, WLAN Point-to-

Point, Wi-Max Long Range Outdoor : 5 Km – 100 Km : Microwave Point-to-Point Long Distance Communication : Across Continents : Satellite

Communication

Frequency BandsBandBand RangeRange

PropagatioPropagationn

ApplicationApplication

VLFVLF 3–30 KHz Ground Long-range radio navigation

LFLF 30–300 KHz GroundRadio beacons and

navigational locators

MFMF 300 KHz–3 MHz Sky AM radio

HF HF 3–30 MHz SkyCitizens band (CB),

ship/aircraft communication

VHF VHF 30–300 MHzSky and

line-of-sightVHF TV, FM radio

UHF UHF 300 MHz–3 GHzLine-of-

sightUHF TV, cellular phones,

paging, satellite

SHF SHF 3–30 GHzLine-of-

sightSatellite communication

EHFEHF 30–300 GHzLine-of-

sightLong-range radio navigation

Wireless LAN Example

Internet Router Switch

Access Point

Access Point

Satellite